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    <script>
        // js中内置提供了很多的类可以直接new实例化对象出来
        let str = new String("不听不听王八念经");
        console.log(str);
        let reg = new RegExp('^1[3-9]\d{9}$');
        console.log(reg.test('111'));
        let num = new Number(10);
        console.log(num+20);
        // Object类在js语句中属于顶级对象（类）
        let obj = new Object;
        console.log(obj)
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